Method for Film Formation, Apparatus for Film Formation, and Computer-Readable Recording Medium

ABSTRACT

Disclosed is a method for film formation, characterized by comprising allowing a treatment gas stream containing a metal carbonyl-containing treatment gas and a carbon monoxide-containing carrier gas to flow into a region on the upper outside of the outer periphery of a substrate to be treated in a diameter direction of the substrate while avoiding the surface of the substrate and diffusing the metal carbonyl from the treatment gas stream into the surface of the substrate to form a metal film on the surface of the substrate.

TECHNICAL FIELD

The present invention generally relates to a manufacturing of asemiconductor device, specifically, to a method for a film formation bythe decomposition of a gas-state base material and a film formingapparatus.

BACKGROUND

In today's semiconductor integrated circuits, the diameter of the viaplug formed with copper (Cu) inside of an insulating film between layersis reduced from 65 nm to 45 nm along with the miniaturization. It isexpected that the diameter of the via plug will be further reduced to 32nm or 22 nm in recent future.

As the semiconductor integrated circuits are miniaturized, it isdifficult to form a bather metal film or a Cu seed layer by theconventional PVD method in a miniaturized via hole or a wiring groove inview of the step coverage. Accordingly, a film forming technology by theMOCVD method or the ALD method is studied in which an improved stepcoverage can be realized at a low temperature that does not damage theinsulating film between layers formed with a low dielectric material(low-K material).

However, the MOCVD method and the ALD method generally use an organicmetal as a base material where metal atoms are combined with an organicgroup. As a result, impurities tend to reside in the formed film, andthus, the quality of the film is not stable even if the step coveragelooks satisfactory. For example, when a Cu seed layer is formed on ametal film of Ta bather by the MOCVD method, the formed Cu seed layertends to generate a condensation thereby making it difficult to form aCu seed layer that stably covers the Ta barrier film with a uniform filmthickness. When an electrolysis plating is performed using the seedlayer that generated the condensation as an electrode, potential defectsmay be included in the Cu layer charged at the wiring groove or the viahole. As a result, problem occurs such as the increase of the electricresistance as well as the electro-migration tolerance or a deteriorationof the stress-migration tolerance.

Thus, a method has been recently suggested where a barrier metal film ora Cu seed layer is formed directly on the insulating film between layersby the MOCVD technology of a metal film using a metal carbonyl basematerial. Metal carbonyl base material is readily dissociated at arelatively low temperature to form a metal layer, and the CO, which isthe ligand of metal carbonyl base material, does not reside in theformed film and immediately discharged to outside of the film formingreaction system. As a result, the barrier metal film or the Cu seedlayer can be formed with a good quality having extremely low impurities.Using this method, a W film can be formed using, for example, W(C)₆, asa barrier metal layer, or a ruthenium (Ru) film can be formed using, forexample, Ru₃(CO)₁₂, as the Cu seed layer.

SUMMARY Problems to be Solved by the Invention

In the mean time, since the metal carbonyl base material has acharacteristic that can be easily dissociated at a relatively lowtemperature, a technology has been proposed where the carbon monoxidegas is supplied as a carrier gas to suppress the dissociation of thebase material during the transport of the base material (base materialsupply system). It is known that the carbon monoxide has an effect tosuppress the dissociation.

For example, in the technology that forms an Ru film as a Cu seed film,Ru carbonyl base material such as Ru₃(CO)₁₂ is supplied to the basematerial supply system using CO gas as a carrier gas to suppress thedissociation of the Ru carbonyl base material during the transportprocedure.

FIG. 1 illustrates the constitution of a film forming apparatus 10,according to the above-described relevant technology.

Referring to FIG. 1, film forming apparatus 10 is exhausted by anexhaust system 11, and includes a processing chamber 12 equipped with asubstrate holding plate 13 that holds a substrate to be processed W. Agate valve 12G is formed at process chamber 12 allowing the substrate tobe processed W passes through.

A heater is embedded in substrate holding plate 13, and the substrate tobe processed W is maintained at a desired process temperature by drivingthe heater through a driving line 13A.

Exhaust system 11 is formed with a turbo molecular pump 11A and a drypump 11B connected serially, and nitrogen gas is supplied to turbomolecular pump 11A via a valve 11 b. A variable conductance valve 11 ais provided between process chamber 12 and turbo molecular pump 11A tomaintain the entire pressure of process chamber 12 being constant. Also,in film forming apparatus 10 of FIG. 1, an exhaustion path 11C isprovided configured to bypass turbo molecular pump 11A for a roughvacuum of process chamber 12 by dry pump 11B, a valve 11 c is providedin exhaustion path 11C and another valve 11 d is provided at thedownstream side of turbo molecular pump 11A.

In process chamber 12, a film forming base material is supplied with agas state via a gas introducing line 14B from a base material supplysystem 14 that includes a base material container 14A.

In the illustrated embodiment, Ru₃(CO)₁₂ which is the carbonyl compoundof Ru is maintained in base material container 14A, and the CO gas isprovided as a carrier gas via bubble ring gas line 14 a that includesMFC (a mass flow controller). As a result, evaporated Ru₃(CO)₁₂ raw gasis supplied to process chamber 12 as a carrier gas that contains the rawgas and CO carrier gas via gas introduce line 14B and shower head 14S,along with the CO carrier gas from line 14 d that includes line MFC 14c.

Also, in the constitution of FIG. 1, along with valves 14 g, 14 h andMFC 14 e, a line 14 f is provided that supplies inert gas such as Ar,and the inert gas is added to Ru₃(CO)₁₂ raw gas supplied to processchamber 12 via line 14B.

Also, in film forming apparatus 10, a controller 10A is provided tocontrol process chamber 12, exhaust system 11 and base material supplysystem 14.

Also, the formation of Ru film on the substrate to be processed W isperformed by Ru₃(CO)₁₂→3Ru+12CO which is the dissociation reaction ofthe Ru₃(CO)₁₂ base material.

The reaction proceeds toward the right side when the partial pressure ofthe CO gas existing in the film forming reaction system is low. As aresult, the reaction proceeds instantly as soon as the CO gas isexhausted outside of process chamber 12 thereby deteriorating the stepcoverage of the formed film. Due to this, the inside of process chamber12 is maintained with a high concentration CO gas atmosphere to preventan excessive reaction of the dissociation (Patent Literature 2).

However, the inventor of the present invention discovered that when filmforming apparatus 10 having a conventional shower head 14S is used asshown in FIG. 1, the deposition rate of the Ru film becomes non-uniformon the substrate W to be processed as shown in FIG. 2. Morespecifically, the deposition rate is higher at the center of thesubstrate than the periphery portion so that a distribution profile isgenerated regarding the deposition rate in the surface. Accordingly, asshown in FIG. 3, it has been discovered that the Ru film formed on thesubstrate to be processed W has a film thickness profile in which thethickness is thicker at the center of the substrate to be processed Wand thinner at the periphery portion, and the variation of the filmthickness in the surface reaches up to 15%.

It is noted that the results of FIG. 2 and FIG. 3 are based on a casewhere an approximately cylindrical processing chamber having an innerdiameter of 505 mm is used as process chamber 12, a silicon wafer Whaving a diameter of 300 mm is held on substrate holding plate 13 as thesubstrate to be processed W, the distance between shower head 14S andthe substrate to be processed W is set to be 18 mm, Ru₃(CO)₁₂ gas issupplied with a flow rate of 1 sccm˜2 sccm as a source gas along with COcarrier gas with a flow rate of 100 sccm, and the Ru film is formed at190° C. of substrate temperature.

Therefore, a technology is required to suppress the deposition ratedistribution profile in the surface or film thickness distributionprofile in the surface.

Patent Literature 1 : Japanese Laid-Open 2002-60944 Patent Literature 2: Japanese Laid-Open 2004-346401 MEANS TO SOLVE THE PROBLEMS

According to an aspect, the present invention provides a film formingmethod characterized by forming a metal film on the surface of thesubstrate to be processed. In the method, a process gas including a rawgas containing metal carbonyl and a carrier gas containingcarbon-monoxide flows to the region of an upper-outer side of thediameter direction than the outer periphery of the substrate to beprocessed while avoiding the surface of the substrate to be processed,and the metal carbonyl is diffused into the surface of the substrate tobe processed by the flow of the process gas to form the metal film.

According to another aspect, the present invention provides a filmforming apparatus characterized by including a substrate holding platethat supports a substrate to be processed, a process chamber thatdefines a process space along with the substrate holding plate, and anexhaust system that exhaust the process space at the upper-outer side ofthe diameter direction of the substrate holding plate. The film formingapparatus further includes a process gas supply unit provided at theprocess chamber to face the substrate holding plate to supply theprocess gas formed with the raw gas and carrier gas to the processspace. In particular, a process gas introduce unit is provided at theprocess gas supply unit in such a way that the process gas flows at theupper-outer side of the diameter direction than the substrate to beprocessed on the substrate holding plate when the substrate holdingplate is viewed from a vertical direction, to the exhaust system in theprocess space while avoiding the substrate to be processed.

According to yet another aspect, the present invention provides acomputer-readable medium characterized by storing the software that,when executed by a general purpose computer, controls a film formingapparatus. The film forming apparatus includes a substrate holding platethat supports a substrate to be processed, a process chamber thatdefines a process space along with the substrate holding plate, and anexhaust system that exhaust the process space at the upper-outer side ofthe diameter direction of the substrate holding plate. The film formingapparatus further includes a process gas supply unit provided at theprocess chamber to face the substrate holding plate to supply theprocess gas formed with the raw gas and the carrier gas to the processspace. In particular, a process gas introduce unit is provided at theprocess gas supply unit in such a way that the process gas flows at theupper-outer side of diameter direction than the substrate to beprocessed on the substrate holding plate when the substrate holdingplate is viewed from a vertical direction, to the exhaust system in theprocess space while avoiding the substrate to be processed. Moreover,the process gas supply unit is provided with metal carbonyl basematerial as the process gas and carbon-monoxide as a carrier gas, andthe general purpose computer controls the temperature of the substrateholding plate to be lower than the temperature at which thecarbon-monoxide suppresses the dissociation of the metal carbonyl.

EFFECTS OF THE INVENTION

According to the present invention, it is possible to suppress thethickness variation of the formed film in the surface by flowing theprocess gas which includes a process gas and a carrier gas to the spaceof an upper-outer side of the diameter direction than the outerperiphery of the substrate to be processed while avoiding the substrateto be processed, and performing the film formation on the surface of thesubstrate to be processed by diffusing the chemical species of theprocess gas into the surface of the substrate to be processed from theflow of the process gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a CVD apparatus having a shower headused for a conventional film forming of an Ru film.

FIG. 2 is a graph that explains the project of the present invention.

FIG. 3 is a graph that explains the project of the present invention.

FIG. 4 illustrates a conventional film formation of the Ru film usingthe shower head.

FIG. 5 is a graph illustrating the pressure distribution and the movingfluid speed distribution of the process gas in the surface that occursduring the film formation of FIG. 4.

FIG. 6 illustrates base material distribution and film thicknessdistribution in the surface generated during the film formation of FIG.4.

FIG. 7 illustrates the outline of the film formation of the Ru filmaccording to the present invention.

FIG. 8 illustrates the outline of the film formation of the Ru filmaccording to the present invention.

FIG. 9 illustrates the outline of the film formation of the Ru filmaccording to the present invention.

FIG. 10 illustrates the outline of the film formation of the Ru filmaccording to the present invention.

FIG. 11 a is a schematic diagram of a film forming apparatus accordingto a first embodiment of the present invention.

FIG. 11 b is a schematic diagram of a film forming apparatus accordingto a first embodiment of the present invention.

FIG. 11 c is a schematic diagram of a film forming apparatus accordingto a first embodiment of the present invention.

FIG. 12 a is a graph illustrating the uniformity of the deposition ratein the surface during the film forming of the Ru film according to thefirst embodiment.

FIG. 12 b is a graph explaining the measurement of FIG. 12 a.

FIG. 13 is a graph illustrating the size effect of a baffle plate in thefilm forming apparatus of FIG. 11 a through FIG. 11 c.

FIG. 14 is a graph illustrating the temperature dependence of thedissociation suppression effect of the Ru carbonyl base material in thecarbon monoxide atmosphere.

FIG. 15 is a graph illustrating the relationship between the uniformityof the Ru film thickness deposited on the substrate to be processed atvarious temperatures and the substrate temperature.

FIG. 16 is a graph illustrating the variation of the Ru film formingspeed according to the temperature changes of the base material chamber.

FIG. 17 is a graph illustrating the variation of the Ru film formingspeed according to the gas flow rate changes of the CO carrier gas.

FIG. 18 illustrates a modified example of the first embodiment.

FIG. 19 illustrates another modified example of the first embodiment.

FIG. 20 is a schematic diagram of a film forming apparatus according toa second embodiment.

FIG. 21 is a first diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

FIG. 22 is a second diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

FIG. 23 is a third diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

FIG. 24 is a fourth diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

FIG. 25 is a fifth diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

FIG. 26 a sixth diagram illustrating a film forming procedure using thefilm forming apparatus of FIG. 20.

FIG. 27 is a seventh diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

FIG. 28 is an eighth diagram illustrating a film forming procedure usingthe film forming apparatus of FIG. 20.

DETAILED DESCRIPTION OF EMBODIMENTS

Inventors of the present invention investigated, as a research on whichthe present invention is based, the cause of the non-uniformity of thedeposition rate and film thickness in the surface as shown in FIG. 2 orFIG. 3 in film forming apparatus 10 using the shower head illustrated inFIG. 1 by examining the moving fluid speed simulation, and obtained thefollowing information.

FIG. 4 illustrates the simulation results of the moving fluid speeddistribution of the process gas flow that occurs in the process spacebetween shower head 14S and the substrate to be processed W when the Rufilm is deposited by film forming apparatus 10 of FIG. 1 by supplyingthe process gas mentioned above from the shower head to the surface ofthe substrate to be processed using the conventional shower head havingthe same discharge holes formed at a surface that faces the substrate tobe processed while exhausting from the exhausting system formed at theouter periphery of substrate holding plate 13. Also, in the simulationresults of FIG. 4, the lighter portion represents the gas concentration,and, accordingly represents the portion where the pressure is high. InFIG. 4, while the gas flow rate at each point is represented as a tinyarrow, the process gas pressure and the distribution of the moving fluidspeed in the surface of the substrate to be processed W are representedas a graph in FIG. 5 since it is difficult to represent in FIG. 4 due tothe resolution.

Referring to FIG. 4, when the gas is discharged from shower head 14S tostage 13, that is, when the gas is discharged from gas discharge holes14 s equally formed at the side of shower head 14S that faces thesubstrate to be processed W disposed on substrate holding plate 13, thedischarged gas flows along the surface of the substrate to be processedto the exhaustion system of the outer periphery with a high speed. Atthat time, as indicated with the dotted line in the figure, the gaspressure is slightly higher near the center of the shower head to whichthe gas is provided from line 14B as shown in FIG. 5. Also, the movingfluid speed of the process gas toward the outer periphery direction isslow at the center of the substrate to be processed. As a result, asshown in FIG. 6, the concentration of the base material becomes highernear the center portion of the substrate to be processed W, andcorresponding to this, the film thickness is increased at the centerportion of the substrate to be processed W thereby generating the filmthickness distribution as shown in FIG. 2.

Meanwhile, a gas flow is formed on the surface of the substrate to beprocessed W along the diameter direction to the outer periphery and themoving fluid speed is increased toward the outer periphery of thesubstrate to be processed W, which can be known from FIG. 4 and FIG. 5.In the simulation of FIG. 4 or FIG. 6, a wafer having a diameter of 300mm is used as a substrate to be processed, and shower head 14S with adiameter of 370 mm has discharge holes 14 s with a diameter of 6.5 mmspaced equally with 13.8 mm intervals. Also, the distance between showerhead 14S and the substrate to be processed W is set to be 18 mm, and thegas is supplied to the shower head with the flow rate of 100 sccm.

Based on the above knowledge, the inventors of the present inventionconceived the formation of the Ru film on the substrate to be processedW as shown in FIG. 7, in which process gas supply member 24S, instead ofshower head 14S, having a gas discharge opening 24 s as a gasintroduction unit at the outer side than the outer periphery of thesubstrate to be processed W, is used to supply the gas to the outer sidethan the outer periphery of the substrate to be processed W. Also, aconstitution is used that exhausts from an exhaust system (not shown)formed at the outer side than the outer periphery of the substrate to beprocessed W to form the Ru film on the substrate to be processed W bythe chemical species of the process gas diffused from the outerperiphery portion to the surface of the substrate to be processed W.

In the constitution of FIG. 7, the direct supply of the gas to thesurface of the substrate to be processed W is blocked by baffle unit 24Bformed at the inner side than opening 24 s of process gas supply member24S, and the chemical species diffused from the gas flowing the outerperiphery of the substrate to be processed W reaches the surface of thesubstrate W.

As a result, as roughly illustrated in FIG. 8, it appears that a uniformbase material concentration is formed on the surface of the substrate tobe processed W and the Ru film is formed on the substrate to beprocessed W with the same thickness.

Each of FIG. 9 and FIG. 10 shows the thickness distribution anddeposition rate distribution, respectively, of the Ru film in thesurface of the substrate when the Ru film is formed with the same filmforming apparatus as used in the experiment of FIG. 2 and FIG. 3 butwith the discharge holes of shower head 14S are blocked except for theholes at the most outer 3 rows. It is noted that the results from FIG. 2and FIG. 3 are overlapped with the results of FIG. 9 and FIG. 10.

Referring to FIG. 9, by supplying the process gas to the outer side thanthe outer periphery of the substrate to be processed W to perform thefilm formation, it is confirmed that the standard deviation (σ) of thefilm thickness variation of the Ru film formed on the substrate to beprocessed W decreased to about 15% to 3% as compared to the case whereshower head 14S having equally formed discharge holes is used, and themaximum thickness difference (Δ) of the surface is decreased from 12.8 Åto 2.8 Å. Likewise, as is clear from FIG. 10, the deposition rate in thesurface is greatly improved as compared to the case where shower head14S is used.

First Embodiment

FIG. 11 a illustrates the constitution of film forming apparatus 40according to the first embodiment of the present invention. Referring toFIG. 11 a, film forming apparatus 40 includes an outside chamber 41exhausted by an exhaust system (not shown), and an inside processchamber 42 formed at the inside of outside chamber 41 and is providedwith an exhaust pipe 42A at the outer periphery. Inside process chamber42 is exhausted via outside chamber 41. Substrate holding plate 43 isprovided at the bottom portion of inner process chamber 42 to supportthe substrate to be processed W and carries a cover ring 43A coupled atthe periphery portion. Cover ring 43A is coupled with the lower endportion of the outside wall of inner process chamber 42, and innerprocess chamber 42 defines a closed process space 42S.

Although, process space 42S is provided with the process gas fromprocess gas supply line 42D, a baffle plate 42B is provided in processspace 42S between opening 42 d at inner process chamber 42 of processgas supply line 42D and the substrate to be processed W on substrateholding plate 43, as illustrated in FIG. 11 b and FIG. 11 c. Thesupplied process gas flows to exhaust pipe 42A through opening 42Cformed at the periphery of baffle plate 42B. Here, FIG. 11 b illustratesthe plan view of baffle plate 42B, and FIG. 11 c is a cross-sectionalview along the line B-B′ of FIG. 11 b.

Referring to FIG. 11 b and FIG. 11 c, baffle plate 42B is formed with aflange unit 42Ba which forms a portion of inner process chamber 42 and abaffle unit 42Bb supported by a bridge unit 42Bc. And for baffle unit42Bb, flange unit 42Ba is supported at inner process chamber 42. Flangeunit 42Ba is provided with screw holes 42Bd to fix into inner processchamber 42.

Substrate holding plate 43 includes a baffle plate 43B which isdifferent from baffle plate 42B. The process gas exhausted from opening42C through exhaust pipe 42A flows into the exhaustion system identicalto exhaust system 11 of FIG. 1 through opening 43 b inside baffle plate43B.

As a result, the desired Ru film is formed by the dissociation from thereaction of the Ru₃(CO)₁₂ molecules described above and diffused fromthe flow of the process gas that passes opening 42C.

Meanwhile, when process gas supply member 24S of FIG. 7 is used insteadof shower head 14S in film forming apparatus 10 of FIG. 1, while thedistribution of the thickness and the deposition rate of the formed Rufilm in the surface are improved as explained in FIG. 9 and FIG. 10, thedeposition rate is decreased drastically as shown in FIG. 10.

Therefore, in order to improve the deposition rate without degrading thedistribution of the Ru film thickness and the deposition rate in thesurface, an experiment has been performed in which the diameter D ofbaffle plate 42, the distance between baffle plate 42B and the substrateto be processed W, the width C of exhaust pipe 42A and the width A ofopening 43 b formed at baffle plate 43B are varied to form the Ru film.Exhaust pipe 42A and opening 43 b are working as an iris or an apertureinserted into the exhaust system of film forming apparatus 40. In theexperiment, the Ru₃(CO)₁₂ raw gas is supplied from process gas supplyline 42D with a flow rate of 1 sccm˜2 sccm along with 100 sccm of COcarrier gas, and the Ru film is formed at 190° C. of substratetemperature.

FIG. 12 a illustrates the experimental results where the horizontal linerepresents the deposition rate and the vertical line represents theposition in the surface of the substrate to be processed W. In FIG. 12a, the position in the surface of the substrate indicates a positionalong the A-A′ line of a silicon wafer having a diameter of 300 mm usedas a substrate to be processed W.

Referring to FIG. 12 a, “Ref” indicates the experiment of FIG. 10, and“I” represents a case where a disk type member having a diameter of 200mm is used as baffle plate 42B, the distance G is set to be 67 mm, thewidth C of exhaust pipe 42A is set to be 19.5 mm, and the width A ofopening 43 b is set to be 77 mm “II” represents a case where a disk typemember having a diameter of 300 mm is used as baffle plate 42B, thedistance G is set to be 67 mm, the width C of exhaust pipe 42A is set tobe 19.5 mm, and the width A of opening 43 b is set to be 77 mm “III”represents a case where a disk type member having a diameter of 300 mmis used as baffle plate 42B, the distance G is set to be 25 mm, thewidth C of exhaust pipe 42A is set to be 19.5 mm, and the width A ofopening 43 b is set to be 77 mm “IV” represents a case where a disk typemember having a diameter of 300 mm is used as baffle plate 42B, thedistance G is set to be 67 mm, the width C of exhaust pipe 42A is set tobe 2 mm, and the width A of opening 43 b is set to be 77 mm “VI”represents a case where a disk type member having a diameter of 300 mmis used as baffle plate 42B, the distance G is set to be 67 mm, thewidth C of exhaust pipe 42A is set to be 19.5 mm, and the width A ofopening 43 b is set to be 2 mm

While the average deposition rate is 3.6 Å/min and the standarddeviation (σ) of the variation in the surface is 2.8% in the “Ref”experiment, the average deposition rate is 11.1 Å/min and the standarddeviation (σ) of the variation in the surface is 11.6% in the experiment“I”. In the experiment “II”, the average deposition rate is 12.4 Å/minand the standard deviation (σ) of the variation in the surface is 5.0%.In the experiment “III”, the average deposition rate is 8.9 Å/min andthe standard deviation (σ) of the variation in the surface is 17.7%. Inthe experiment “IV”, the average deposition rate is 15.0 Å/min and thestandard deviation (σ) of the variation in the surface is 5.5%. In theexperiment “V”, the average deposition rate is 14.9 Å/min and thestandard deviation (σ) of the variation in the surface is 5.7%. In theexperiment “VI”, the average deposition rate is 15.5 Å/min and thestandard deviation (σ) of the variation in the surface is 5.4%.

Referring to FIG. 12 a, as illustrated in FIG. 11 a, it can be knownthat the deposition rate is improved by making the conductance of theexhaustion path from processing chamber 42 at exhaust pipe 42A andopening 43 b small. Moreover, it can be also known that the distributionof the deposition rate in the surface is improved when the diameter D ofbaffle plate 42B is 300 mm which is the same as the diameter of thesubstrate, rather than 200 mm

As described above, it is confirmed that the uniformity of the filmformation on the substrate to be processed strongly depends on thediameter D of baffle plate 42B, and the inventors of the presentinvention investigated the uniformity of the Ru film thickness in thesurface obtained when the diameter D of baffle plate 42B is furtherincreased to 340 mm in film forming apparatus 40 of FIG. 11 a or FIG. 11c. The results are shown in FIG. 13 where the horizontal line representsthe position in the surface along the line A-A′ of FIG. 12 b, and thevertical line represents the standardized thickness of the Ru film atthe center portion (substrate inside position=0 mm) of the substrate tobe processed W, as in FIG. 12 a.

Referring to FIG. 13, the uniformity inside the surface is superior whenthe diameter D of baffle plate 42B is 300 mm (the standard deviation ofthe variation of the film thickness is 5.9%) as compared to when thediameter D of baffle plate 42B is 200 mm (the standard deviation of thevariation of the film thickness is 11.6%). Specifically, when thediameter D is changed from 200 mm to 300 mm, the degree of theimprovement of the uniformity in the surface is extremely large suchthat the standard deviation of the film thickness variation in thesurface ranges from 11.6% to 5.9%. Accordingly, it can be decided thatthe improvement of the uniformity of the formation of the Ru film on thesubstrate to be processed W is more effective when the diameter of thebaffle plate 42B is larger than that of the substrate to be processed W.

However, as described above, in the present invention, the dissociationis suppressed during the transport of the base material by using the COas a carrier gas during the formation of the metal film by the CVDmethod using the metal carbonyl base material such as Ru. Also, as inthe present embodiment, in a substrate processing apparatus having anapparatus where the metal carbonyl is diffused into the center portionof the substrate to be processed W and the dissociation during thediffusion is suppressed and transported by using the carbon monoxideatmosphere, it is important to maintain the suppression effect of thedissociation of the metal carbonyl during the diffusion by the CO toperform a film formation that has an excellent characteristic of, forexample, the step coverage.

FIG. 14 is a graph that illustrates the effect of the substratetemperature with respect to the dissociation suppression effect by theaddition of the CO gas to the base material of Ru₃(CO)₁₂. In FIG. 14,the vertical line represents the deposition rate of the Ru film, and thehorizontal line represents the substrate temperature. Also, the line Iindicates the formation of the Ru film where the CO is not added to theRu₃(CO)₁₂, and the line II indicates the formation of the Ru film fromthe base material of Ru₃(CO)₁₂ under the CO atmosphere.

Referring to FIG. 14, it is confirmed that when the substratetemperature is below 200° C., the deposition rate of Ru₃(CO)₁₂ filmunder the CO atmosphere is very low and the dissociation is practicallysuppressed. However, it is also confirmed that when the substratetemperature exceeds 200° C., the suppression effect is graduallydecreased, and the effectiveness is almost lost when exceeding 230° C.Accordingly, when the temperature of the substrate to be processed W isset to be 235° C. or higher in film forming apparatus 40 of FIG. 11 a orFIG. 11 c, the film is preferentially formed at the periphery of thesubstrate and the uniformity of the desired film formation in thesurface is damaged.

In view of this, when a metal film is formed in film forming apparatus40 of FIG. 11 using the metal carbonyl base material, for example, whenthe Ru film is formed using Ru₃(CO)₁₂ base material, it is preferablethat the substrate temperature is set to be 230° C. or lower where thedissociation suppression effect of the metal carbonyl by the CO iseffectively act. Also, it is more preferable to set the substratetemperature to be 200° C. or lower because the dissociation suppressioneffect acts sufficiently at the temperature range. Moreover, since thedissociation of Ru₃(CO)₁₂ base material begins at 100° C. or higher whenthe CO exists, it is preferable to set the substrate temperature to be100° C. or higher.

Also, the deposition rate of the Ru film on the substrate to beprocessed W can be improved as well by increasing the temperature of thebase material container that constitute a portion of base materialsupply system 14 as shown in FIG. 1.

FIG. 16 is a graph that illustrates the variation of the uniformity ofthe deposition rate in the surface when the temperature of a basematerial container 14A is changed in the film forming apparatus havingthe constitution of FIG. 7 that uses process gas supply member 24Sinstead of shower head 14S in film forming apparatus of FIG. 1.

In FIG. 16, data “I” indicates a case where the temperature of the basematerial container is set to be 75° C. and corresponds to the result ofprior FIG. 10. In contrast, data “II” is a case where a baffle plateidentical to baffle plate 43B of FIG. 11 a is provided around substrateholding plate 13 in the constitution of FIG. 7. It is confirmed thatwhile other conditions are the same as in data “I”, the averagedeposition rate is increased up to 6 Å/min because the conductance ofthe exhaust path is reduced. In data “II”, the variation of thedeposition rate of the formed Ru film in the surface is suppressed as 2%of standard deviation, and an improved uniformity in the substratesurface is achieved.

Also, in FIG. 16, data “III” indicates the distribution of thedeposition rate in the surface when the maintaining temperature of basematerial container 14A is set to be 85° C. in the film forming apparatuswhere the baffle plate is added to the constitution of FIG. 7 based onthe constitution of FIG. 1. As can be known from FIG. 16, the averagedeposition rate is improved 60% from 6 Å/min to 10 Å/min by increasingthe maintaining temperature of base material container 14A from 75° C.to 85° C. and maintaining other conditions to be the same. In data “III”as well, the variation of the deposition rate in the surface issuppressed by 2.6% of standard deviation to obtain an improveduniformity in the substrate surface.

Also, in the constitution of FIG. 7 through FIG. 11, the deposition rateof the Ru film can be improved by maintaining the partial pressure ofthe CO gas in the process chamber and by increasing the flow rate of theCO carrier gas.

FIG. 17 is a graph that illustrates the uniformity of the depositionrate of the Ru film in the surface when only the flow rate of the COcarrier gas is increased from 100 sccm to 200 sccm and other conditionsare maintained to be the same, in film forming apparatus 40 of FIG. 11 athrough FIG. 11 c

Referring to FIG. 17, it is indicated that the average deposition rateis 14.9 Å/min when the flow rate of CO carrier gas is 100 sccm. However,when the CO carrier gas flow rate increases to 200 sccm, the depositionrate increases about 30% to 19.4 Å/min Also, the variation of thedeposition rate in the surface is maintained in the range of 5.5%˜5.7%of standard deviation under any circumstances and an excellentuniformity in the substrate surface is achieved.

FIG. 18 and FIG. 19 each illustrates the constitution of a baffle plate52B as a modified embodiment of baffle plate 42B of FIG. 11 b.

Referring to FIG. 18 and FIG. 19, when viewed from a vertical directionwith respect to substrate holding plate 43, baffle plate 52B is providedwith 3 rows of opening 52 b or 2 rows of opening 52 c positioned alongthe outer periphery of the substrate to be processed W corresponding toopening 42C of FIG. 11 a through FIG. 11 c. For example, it is possibleto supply the process gas to the outside of outer periphery of thesubstrate to be processed W as in film forming apparatus 40 of FIG. 11 aby setting the diameter of opening 52 b or 52 c to be 6.5 mm and thedistance to be 13.8 mm

Second Embodiment

FIG. 20 illustrates the constitution of film forming apparatus 60 in anidling state, according to the second embodiment. Referring to FIG. 20,film forming apparatus 60 has a structure in which an outer chamber 62is fixed on a base unit 61 and an inner process chamber 63 formed with aprocess gas introduce opening 63A is installed to a flange unit 63F.Outer chamber 62 corresponds to outer chamber 41 of FIG. 11 a, and acarry in/out space 62A for the substrate is provided at the side wall.

Meanwhile, inner process chamber 63 corresponds to inner process chamber42 of FIG. 11 a and has a cylindrical shape. Also, process gas introduceopening 63A is provided on the upper portion of inner process chamber 63roughly coinciding with the central shaft. Also, a cool/heat medium path63B is provided in inner process chamber 63 to control the temperature.

The bottom portion of inner process chamber 63 is opened, and asubstrate holding plate 64 corresponding to substrate holding plate 43of FIG. 11 a is provided at the front end of a support unit 64A coveringthe bottom portion. As a result, inner process chamber 63 along withsubstrate holding plate 64 defines a process space 63S.

Support unit 64A of substrate holding plate 64 is maintained by anactuator 61A and an arm 61 a with respect to base unit 61, and theactuator may be either an electronic type or an oil pressure type. Anup/down movement indicated as arrows is performed by driving actuator61A. Also, the combined portion of support unit 64A and outer chamber 62is sealed by a seal member 62C that includes bellows 62 c.

The bottom portion of outer chamber 62 is provided with an exhaust pipe(not shown), and by connecting exhaust system 11 of FIG. 1, processspace 63S is exhausted through the exhaust path formed in betweensubstrate holding plate 64 along with support unit 64A and outer chamber62.

As shown in FIG. 20, a flange-type baffle unit 64F is provided nearsubstrate holding plate 64, and a continuous exhaust pipe 63C isprovided in between baffle unit 64F and the bottom portion of innerprocess chamber 63. Exhaust pipe 63C is provided continuously at anouter side than the outer periphery of the substrate to be processed Wheld on inner process chamber 63. The conductance of exhaust pipe 63Cvaries by moving substrate holding plate 64 into up/down direction.

A heater 64H is embedded in substrate holding plate 64 and driven by thedriving current from an electrode 64 h. Also, a lifter pin 64L is formedon substrate holding plate 64 with the lower end portion 641 including apin driving unit is fixed to a portion of outer chamber 62. Therefore,when substrate holding plate 64 is descended by actuator 61A, lifter pin64L is protruded to an upper direction than substrate holding plate 64thereby lifting the substrate to be processed on substrate holding plate64. Also, a cool/heat medium path 64B is provided at the lower part ofheater 64H inside substrate holding plate 64 to pass the cool/heatmedium.

Also, substrate holding plate 64 includes a cover ring 64R which iscoupled to the outer periphery of the substrate to be processed heldthereon. Cover ring 64R passes through substrate holding plate 64 andextends to the lower direction. Also, cover ring 64R includes a driveunit 64 r which is coupled to a portion of outer chamber 62 and clearsthe combination with the substrate to be processed when substrateholding plate 64 descends.

Also, in film forming apparatus 60 of FIG. 20, a baffle plate 65corresponding to baffle plate 42B of FIG. 11 a is provided inside innerprocess chamber 63 facing the substrate to be processed on substrateholding plate 64 and with a diameter bigger than that of the substrateto be processed. Also, opening 65A corresponding to opening 42C of FIG.11 a is provided at the outer side than the outer periphery of thesubstrate to be processed on substrate holding plate 64. Baffle plate 65includes flange unit 65F at the outside of opening 65A, and flange unit65F is fixed to the upper half body 63U of inner process chamber 63 byscrew 65 d. The lower portion of flange unit 65F is fixed to the lowerhalf body 63L of inner process chamber 63 by screw 65 e. Upper half body63U and lower half body 63L along with flange unit 65F form innerprocess chamber 63.

Also, film forming apparatus 60 of FIG. 20 is equipped with a controller66 formed with a general purpose computer loaded with a program tocontrol the entire operation including the operation of actuator 61A.

Next, referring to FIG. 21 through FIG. 28, an exemplary process offorming the Ru film on a silicon substrate is described using filmforming apparatus 60 of FIG. 20.

Referring to FIG. 21, actuator 61A is driven toward the lower directionby controller 66, and substrate holding plate 64A is separated frominner process chamber 63 and descends. As a result, exhaust pipe 63C iswidely opened corresponding to substrate carry in/out space 62A of outerchamber 62. In the state of FIG. 21, exhaust pipe 64C has the width of32.3 mm in an up/down direction. In the state of FIG. 21, as substrateholding plate 64 descends, lifter pin 64L protrudes from the surface ofsubstrate holding plate 64, and cover ring 64R also changes itspositional relationship which is separated toward the upper directionthan the surface of substrate holding plate 64.

Next, as illustrated in FIG. 22, an arm 71 of the substrate transportmechanism supporting the substrate to be processed W from substratecarry in/out space 62A is inserted into a position between lifter pin64L and cover ring 64R through the widely opened exhaust pipe 63C, andas illustrated in FIG. 23, the substrate to be processed W is separatedfrom arm 71 by driving drive unit 641 to ascend lifter pin 64L.

Also, as illustrated in FIG. 24, arm 70 is retreated from carry in/outspace 62A and the gate valve (not shown) is closed.

Next, as illustrated in FIG. 25, actuator 61A is driven and substrateholding plate 64 is elevated putting support unit 64A in between, andthe substrate to be processed W supported on lifter pin 64L is supportedby substrate holding plate 64. At this state, exhaust pipe 63C has a 10mm width along the up/down direction.

Next, as illustrated in FIG. 26, actuator 61A is driven by a tinyamount, and substrate holding plate 64 is elevated by a tiny amountthereby setting the width of exhaust pipe 63C to be 8 mm Also, at thisstate, cover ring 64R is combined to the side surface of the substrateto be processed W and maintained.

Also, in the process of FIG. 27, substrate holding plate 64 is elevateda little further by the driving of actuator 61A and the distance betweenbaffle plate 65 and the substrate to be processed W is set to be 67 mmAlso, the up/down direction width of exhaust pipe 63C is set to be 2 mm,and the process gas containing Ru₃(CO)₁₂ gas and CO carrier gas isintroduced from process gas introduce opening 63A. The introducedprocess gas is exhausted from opening 65A of the outer periphery ofbaffle plate 65 to exhaust pipe 63C. As a result, the Ru film isdeposited with an identical rate in the surface of the substrate to beprocessed W out of the Ru₃(CO)₁₂ molecules diffused from the process gasflow, and the Ru film having an improved uniformity is deposited on thesurface of the substrate to be processed W. Also, the process gasdischarged from exhaust pipe 63C is exhausted from the exhaust pipe (notshown) through exhaust path 62B formed between outer chamber 62 andsubstrate holding plate 64, or between support unit 64A.

In the process of FIG. 27, by controlling the temperature of thesubstrate to be processed W with 200° C. or higher and 230° C. or lower,the preemptive Ru film deposition at the periphery of the substrate tobe processed W is effectively suppressed by the CO gas and the problemof a selective deposition of the Ru film at the periphery of thesubstrate to be processed W, as described in FIG. 15, can be avoided

After the process of FIG. 27, although the description is omitted, thesubstrate to be processed W is taken out by arm 71 of the substratetransport mechanism, the condition of film forming apparatus 60 isreturned to the condition of FIG. 20 as illustrated in FIG. 28, and theinside of inner process chamber 63 is purged.

In the present embodiment, as for baffle plate 65, not only the baffleplate described in FIG. 11 b and FIG. 11 c but also the baffle platedescribed in FIG. 18 and FIG. 19 may be used.

Also, in the present embodiment, by flowing the cool/heat medium tocool/heat medium path 63B or 64B, the temperature of outer chamber 62and inner process chamber 63 can be maintained at 80° C. and thedeposition of the Ru film other than the substrate to be processed W canbe suppressed.

As can be known from the above description, the present invention is notlimited to the method of the Ru film formation in which Ru₃(CO)₁₂ gas isused as a base material and the CO gas is supplied along with, but maybe effective to form other metal film such as W, Co, Os, Ir, Mn, Re, Moby supplying the carbonyl base material along with the CO gas.

While preferred embodiments are described above, the present inventionis not limited to the specific embodiments, but various modificationsmay be possible within the scope of the claims.

The present invention is based on and claims priority from JapanesePatent Application No. 2008-084551 filed on Mar. 27, 2008, thedisclosure of which is incorporated herein in its entirety by reference.

1. A method for forming a metal film on the surface of a substrate to beprocessed by comprising: flowing a process gas including a raw gascontaining a metal carbonyl and a carrier gas containing carbon monoxideto a region of an upper-outer side of a diameter direction than theperiphery of the substrate to be processed; and diffusing the metalcarbonyl to the surface of the substrate to be processed from the flowof the process gas thereby depositing the metal film on the surface ofthe substrate to be processed.
 2. The method according to claim 1,further comprising flowing the process gas through a baffle plate thathas an outer periphery larger than that of the substrate to be processedand is positioned to face the surface of the substrate to be processed.3. The method according to claim 1, further comprising forming anexhaust pipe that forms an iris at the region of an upper-outer side ofa diameter direction, and controlling the deposition rate on the surfaceof the substrate to be processed by controlling the iris.
 4. The methodaccording to claim 1, wherein the film formation is performed at asubstrate temperature where a dissociation of the metal carbonyl issuppressed by a carbon monoxide gas.
 5. The method according to claim 1,wherein the film formation is performed at a substrate temperature of230° C. or lower. 6-16. (canceled)